# Calculate the partial pressure of oxygen in the air

1) You begin your survey on the big island of Hawaii in the desolate region surrounding the peak of Mauna Loa (elevation 4169 m, ambient pressure 452 mmHg) where you find a group of nesting seabirds. The relative humidity is 40% and the temperature is 10ºC. You are interested in analyzing gas exchange in the eggs so you must first calculate the partial pressure of oxygen in the air.

2) What is the partial pressure of oxygen in the air that has entered your lungs (before any oxygen has been exchanged with the blood) at the seabird nesting site described above at the peak of Mauna Loa?

3) As you descend down the windward (and thus rainy) side of the volcanic crater, you discover a series of small pools (elevation = 2350 m, ambient pressure 571 mmHg) containing small crustaceans. What is the nitrogen content (ml N2 / l water) of the water? The temperature is 20ºC and the relative humidity is 100%.

4) Near the base of the volcanic crater you find warm (30ºC) caves in the lava (relative humidity 75%, ambient pressure = 750 mmHg) with an interesting assemblage of lizards. What is the partial pressure of carbon dioxide in the air in the caves?

5) Upon further exploration you find that the warm (30ºC ) caves extend some distance into the mountain and descend to considerable depth, 330 m below sea level (ambient pressure = 790 mmHg). At their base you find a series of freshwater pools inhabited by an endemic fish species. The relative humidity in this portion of the cave is 100%. What is the tension of oxygen in the water?

6) Suppose that you are conducting a series of experiments on the effect of reduced oxygen on the physiology of several freshwater fish species. The experimental chamber is covered and is arranged such that the pressure above the water surface can be varied. Before placing the fish in the chamber, you measure the oxygen content of the water to be 5.5 ml O2/ liter water. The temperature is 15 ºC, the relative humidity in the chamber is 100%, and the water is at equilibrium with the air in the chamber. What is the tension of
oxygen in the water?

7) If you listen to the local weather forecast, you have no doubt heard the “dew point” reported. The dew point is the temperature to which a given parcel of humid air must be cooled for water vapor to condense into liquid water. If a sample of air contains approximately 13 mg H2O per liter air, the dew point is _____ºC Write the letter of the correct answer in the blank on the left side of the page (2 points each).

8) ___ During a complete opercular pumping cycle, the pressure in the opercular cavity of a fish is (a. always higher than; b. always lower than; c. mostly higher than; d. mostly lower than) the pressure in the buccal cavity.

9) ___ When a bird exhales, air flows (a. from the anterior air sacs into the lungs; b. from the posterior air sacs to the mouth; c. from the lungs into the posterior air sacs; d. from the posterior air sacs into the lungs).

10)___ Suppose that you measured the maximum oxygen extraction (ml oxygen removed by the lungs per liter air) of a mourning dove and a chipmunk of the same body mass. The oxygen extraction of the chipmunk would likely be (a. greater than; b. less than; c. equal to) that of the dove.

11)___ Suppose that you found a mutant trout species that shows concurrent flow, rather than countercurrent flow of the blood in the gills. You predict that the blood leaving the gills would (a. always have a higher; b. sometimes have a higher; c. never have a higher) oxygen tension than the water leaving the gill chamber.

The flow of blood through a branched portion of an unusual circulatory system is illustrated from the side in the diagram above.

12)___ The highest velocity flow would be found in (a. position 1; b. position 2; c. position 3; d. position 4)

13)___ The highest pressure would be found at (a. position 1; b. position 2; c. position 3; d. position 4)

14)___ The highest wall tension would be found at (a. position 1; b. position 2; c. position 3; d. position 4)

15)___ If the blood flow stopped, the lowest pressure would be observed at (a. position 1; b. position 2; c. position 3; d. position 4)

16)___ At the normal pH of mammalian blood, most of the carbon dioxide in the blood is present as (a. carbonic acid; b. carbonate ion; c. bicarbonate ion).

17)___ If all other factors (including blood pressure) were held constant, an increase in the plasma colloidal osmotic pressure would cause (a. an increase; b. a decrease; c. no change) in the volume flow rate of lymph from the tissues.

18)___ If an insect undergoing cyclical respiration is placed in pure oxygen before the spiracles close so that the tracheal system is filled with oxygen only, the negative pressure observed when the spiracles close would be expected to be (a. greater than; b. less than; c. equal to) that observed in normal atmospheric air.

19)___ Suppose that you have a large container of water that has been equilibrated with atmospheric air. You introduce a tiny bubble into the water containing 50% nitrogen and 50% oxygen. The concentration of nitrogen in the bubble would (a. increase; b. decrease; c. remain unchanged) as the bubble comes to equilibrium with the water.

20)___ Suppose that you are setting up an aquarium for tropical reef fish. You begin by filling the aquarium with tap water and allow it to stand for 24 hours in order for the fluoride aIDed by OWASA to diffuse out. Over this time the water comes into equilibrium with the atmosphere. You then aID artificial sea salt to raise the salinity to that of ocean water. If you measured the oxygen content (mlO2/lwater) of the aquarium water before and then after you aIDed the salt you would expect that the oxygen content would (a. increase; b. decrease; c. remain unchanged) after aIDition of the salt. (Assume that the saltwater has also had sufficient time to reach
equilibrium).

21)___ Once the salinity has been adjusted properly, you then install a heater to bring the temperature up to that of tropical reef water appropriate for the fish. If you measured the oxygen content (mlO2/lwater) before installing the heater and then once again after installing the heater, the oxygen content at equilibrium would (a. increase; b. decrease; c. remain unchanged).

Oxygen-hemoglobin dissociation curves (a, b, & c) are graphed to the right. Fill in the blank with the letter indicating the correct curve.

If curve b represents blood before entering the capillaries of the lungs, curve 22)____ would represent the blood leaving the
lung.

If curve b represents the blood of a hippopotamus, curve 23)____ would represent the blood of a hamster.

If curve b represents blood at 40ºC, curve 24)____ would represent the blood at 37ºC.

If curve b represents blood at pH 7.2, curve 25)____ would represent the blood at pH 7.6.

An decrease in the concentration of 2,3-diphosphoglycerate would shift the curve labeled b towards curve 26) ____.

If curve b represents the blood of a squirrel fetus, curve 27) ____ likely represents the blood of the mother.

28)___ The lowest velocity of blood flow is found in the (a. aorta; b. capillaries; c. arterioles; d. vena cava).

29)___ At a given CO2 pressure (mmHg) the total carbon dioxide content (ml CO2 / l blood) of oxygenated blood is (a. greater than; b. less than; c. equal to) that of deoxygenated blood.

30)___ Suppose that you are conducting an experiment on samples of mammalian blood in which you determine the change in P50 for a given change in pH of the blood sample. If the change in P50 was 12 mmHg for a given change in pH of the blood of an rhinoceros, the most likely change in P50 for an identical change in pH of the blood of an rat would be (a. 0 mmHg; b. 6 mm Hg; c. 20 mmHg).

31)___ As normal blood flows from the capillaries to the veins, its apparent viscosity (a. increases; b. decreases; c. remains the same)

32)___ Suppose that a company is developing oxygen binding molecules for use as artificial blood in patients who have suffered injury and blood loss. The company has synthesized two different molecules; molecule version 1 has a MW of 45,000 and molecule version 2 has a MW of 20,000. Both versions have 2 binding sites for oxygen.

You are asked to characterize their oxygen binding properties and find that both show facilitated diffusion when tested at the same concentration in the apparatus developed by Scholander. The facilitation measured for version 1 would likely be (a. greater than; b. less than; c. equal to) that measured for version 2.

33)___ If the flow of fluid in a pipe is turbulent, increasing the (a. density; b. diameter; c. viscosity; d. velocity) may cause a transition to laminar flow.

34)___ The lowest blood pressures are observed in the (a. aorta; b. arterioles; c. capillaries; d. veins).

35)___ During the fluttering phase of cyclical respiration in insects, the partial pressure of carbon dioxide in the tracheal
system (a. increases; b. decreases; c. remains approximately constant).

36)___ If you monitored the respiratory gases in a bird undergoing normal respiration, you would find the partial pressure of carbon dioxide in the posterior air sacs to be (a. greater than; b. less than; c. equal to) the partial pressure of carbon dioxide in the anterior air sacs.

Fill in the blank with the correct number, word or short phrase.

Suppose that you are using a hose with a radius of 2cm to fill the artificial seawater system in your laboratory. If all other factors are held constant, replacing the hose with a 5cm radius hose of identical length would increase the flow rate by a factor of 37)__________?

The gut of termites is packed with flagellates and with bacteria. What is the role of each in the digestion and nutrition of termites?

Flagellates 38)_____________________________________________________________
Bacteria 39)_______________________________________________________________

Most animals that use gills for respiratory exchange have mechanisms that move the water relative to the gills. This is necessary because if a gill removes oxygen from completely still water, the immediately adjacent 40)______________________________________ of water will soon be depleted of oxygen.

In bird lungs, air flows continuously past the exchange surface through the finest branches of the air passages called 41)_________________________________________ which permit through passage of air.

The tracheae of the insect respiratory system branch and ramify and extend to all parts of the body. The finest branches, the 42)____________________________________, may be as small as 0.5 µm in diameter and can extend into individual cells, such as muscle fibers.

43)_________________________________ is a copper-containing respiratory pigment that occurs only in mollusks and arthropods, but nevertheless, next to hemoglobin, it is the most widely distributed respiratory pigment.

The flow of air in the bird lung is in fact not an ideal countercurrent exchange system, but rather a

44)_________________________________ type of flow, which is not quite as effective as a true countercurrent system in achieving maximum advantage in gas exchange.

Some fish, such as tuna, cannot be kept alive in captivity unless they can swim continuously, typically in a large ringshaped tank. Such fish swim with their mouths partly open, there are no visible breathing movements and water flows continuously over the gills; this is called 45)__________________________________________.

Many rodents as well as rabbits and hares form a special kind of feces from the contents of the cecum, and these are reingested in a process called 46)___________________________________so that the food passes through the entire digestive tract a second time.

Microbial protein synthesis in the rumen is of special importance when ruminants are fed on low-grade feed. Rather than being excreted 47)_________________________________ reenters the rumen, in part through the rumen wall and in part with the saliva. This “waste” product is then hydrolyzed to carbon dioxide and ammonia, the latter being used by the microorganisms for resynthesis of protein.

The enzymes that digest proteins are divided into two groups, according to where on the protein molecule they act. 48)______________________________________________hydrolyze a terminal peptide bond in a long peptide chain;
49)______________________________________________ act in the interior of the peptide chain.

Fats are highly insoluble in water and as a result are not easily hydrolyzed. The 50)______________________________, secreted by the liver, serve to emulsify the fat and bring it into contact with lipase, the fat-hydrolyzing enzyme.